A cutting apparatus for slicing plastic foam solids or the like (hereinafter referred to as a foam body or block) can comprise a cutting wire system having a plurality of cutting wires spanning two parallel supporting rods and attached substantially perpendicularly to them so that a foam body to be cut into slabs by parallel cuts can be passed through the array of cutting wires between the supporting rods.
An oscillating drive is operatively connected to the supporting rods so as to angularly oscillate the supporting rods in opposing rotational directions and therefore to reciprocate the wires to and fro lengthwise.
The cutting wires can be attached eccentrically to the outer peripheries of the supporting rods and are energized with an electric current so that resistive heating is generated and enables each wire to cleanly slice through the body.
In the apparatus of this type described in U.S. Pat. No. 4,222,299, the planes of both cutting wire positions are coincident, i.e. all the cutting wires lie substantially in a single plane.
The ends of the cutting wires of both sets of oppositely moving cutting wires are attached to both supporting rods on the same outer peripheral side, and, of course, at one end by a coil spring and the other end by an inextensible attachment means. The coil springs of one wire set are associated with a first supporting rod and the inextensible attachment means thereof with the second supporting rod. The inextensible attachment means of the other set are affixed to the first rod and the coil springs of this set are attached to the second rod. The supporting rods are angularly oscillated in opposing senses to reciprocate the sets of wires in opposite directions with periodic variations of the respective coil spring lengths.
This prevents imbalanced forces and moments from developing which would affect the plastic foam body.
Advantageously in this prior art construction, cost is minimal because collectively only two oscillating supporting rods and a correspondingly simple oscillating drive are required.
In practice, however, there is the disadvantage that the coil springs produce significant tension in the cutting wires due to the periodic length variation of the wires during operation which is particularly a problem for the eyelet attachments at the ends of the wire which are comparatively easily broken or worn out.
U.S. Pat. No. 4,018,116 also describes an apparatus for cutting a plastic foam solid or the like comprising a cutting wire system having two cutting wire sets, wherein the cutting wires of one set move back and forth opposite to the cutting wires of the other set. Here the cutting wires are attached at their ends to two supporting rods which are angularly oscillated about their longitudinal axes in the same sense of rotation.
Both these supporting rods are associated with the cutting wires of one cutting wire set, while for the cutting wires of the other cutting wire set, two additional supporting rods are required and are angularly oscillated in the same rotational sense, which is however opposite to the sense of angular oscillation of the first pair of supporting rods mentioned.